1. Field of the Invention
The present invention relates to a method of transfer of a magnetic toner to a paper sheet. Specifically, the present invention relates to a method of transfer of a magnetic toner, which has improved transferring characteristics. The present invention also relates to a recording device used in the method of transfer.
Conventional method of development employing a developer for electrophotography, are divided roughly into two main types; a one-component and a multiple-component method of development. The one-component methods of development uses a single-component developer which consists essentially of a magnetic toner.
The following is a description of the developing device employed in electrophotography (i.e. the recording device) and used in the above-mentioned one-component method of development. FIG. 6 shows the conventional developing device. The developing device is composed of a photoconductor 11, an electrostatic generator 12, an exposer 13, a developer 14, a transferring corona generator 15, a fixer device 17, and the like. An electrostatic generator 12, an exposer 13, a developer 14, a transferring corona generator 15, and a fixer device 17 are each positioned around the photoconductor 11. The mechanics of these devices are explained hereinbelow. When the photoconductor 11 rotates in the direction shown by the arrow in FIG. 6, the surface of the photoconductor 11 is uniformly charged by the electrostatic generator 12. Electrostatic latent images are formed by selectively exposing the surface of the photoconductor 11, depending on an image or a picture signal. The electrostatic latent images are developed by applying magnetic toners to the electrostatic latent images with the developer 14. A paper sheet 16 is superimposed on the surface of the photoconductor 11 maintaining the developed magnetic toners. Then the paper sheet 16 is oppositely charged, with respect to the charge of the magnetic toner, by the transferring corona generator 15, and the paper sheet 16 is subsequently torn off from the surface of the photoconductor 11. The image is then recorded by fixing the magnetic toners onto the paper sheet 16 with the fixer device 17.
Besides the above-mentioned method of transfer which employs a corona generator, representative examples of the methods of transferring the magnetic toners maintained on the surface of the photoconductor to the paper sheet include a method using a roller, and a method using a belt, and the like.
In recent years, the electro-photography recording device has become increasingly popular, and a recording device that uses less electrical power has been in demand. Therefore, in order to satisfy such a demand, a recording device which can use magnetic toners which have a low resistance capacity (i.e. approximately 10.sup.4 ohm cm or less) has been developed. If the magnetic toner has such a low resistance capacity, then the magnetic toner can be applied to a low potential developing system in which the voltage used in developing is 100 V or less. However, the magnetic toner has such a low capacity for resistance that, consequently, there is scattering. The scatter occurs by an electrical charge generated by the transferring corona generator during the process of transferring magnetic toners from the photoconductor to the paper sheet, and by an electrical charge generated on the surface of the paper sheet. As a result, it is impossible to obtain good quality transferred images. The phenomena which cause this problem are explained below. For example, when the magnetic toners are transferred close to where the transferred image is developed, the resolution of the image deteriorates. This phenomenon is called "blur". Moreover, when the magnetic toners on the photoconductor are not uniformly transferred onto the paper sheet and part of the magnetic toners remain on the photoconductor, then part of the image is not transferred. This phenomenon is called "white spot within character". Besides the above-mentioned problems, a practical image density cannot be obtained, and also the efficiency of transfer is low. If the method of transfer using a roller is applied, relatively good transferring properties cannot be obtained.